1. Field of the Invention
The present invention relates to a roller which is exposed to a very heavy load, is required to have a suitable elastic force and abrasion resistance, and is structured so as to mount a tire for a high speed rotation and a heavy load, such as in an escalator, a moving walkway and the like, in which safety is highest priority, and particularly to a roller mounted so that the tire and the bearing do not skip even when the heavy load is applied at a time of starting the rotation and by a sudden stop, and a method of producing the same.
2. Prior Art
This kind of conventional roller is used on a rotating portion which rotates at a high speed, is exposed to a heavy load, is required to have a suitable elastic force and abrasion resistance, and ensures safety with the highest priority in environments such as transfer rollers, elevators, guide rollers, escalators, moving walkways, and the like, when mounting a synthetic resin tire. The roller of this kind is structured so that a synthetic resin tire is integrally adhered to a smooth outer peripheral surface of an outer race in the bearing. Further, the tire provided in this kind of bearing is required to have an abrasion resistance and a suitable elastic force together with a resistance against high speed rotation and a heavy load. The roller, which is structured so that the synthetic resin tire used in the rotating portion in which safety is required as the highest priority, is mounted to the bearing, is formed in such a manner that the tire adhered to the outer race of the bearing in a surrounding manner is formed in two layers, a tire outer peripheral portion made of a soft synthetic resin to meet a requirement of the abrasion resistance and the elastic force, and a tire base or inner portion directly adhered to the outer race of the bearing made of a hard synthetic resin to bear a resistance against the high speed rotation and the heavy load. There is suggested a roller which is structured so that the synthetic resin tire integrally adhered to the bearing in a surrounding manner is constituted by having two layers, hard and soft, respectively, a synthetic resin tire, and a method of producing the same.
Conventionally, in this kind of roller structured so that the synthetic resin tire is adhered to the outer race of the bearing, the synthetic resin tire used as the tire is integrally adhered to the outer race of the bearing in a surrounding manner. This conventional roller as used for elevators, escalators, transfer rollers, guide rollers, moving walkways, and the like, rotates at a high speed, is exposed to a heavy load, is used under very severe conditions, is required to have a suitable elastic force and an abrasion resistance in accordance with its use, and is required to ensure safety as the highest priority. Accordingly, in order to obtain a stronger adhesion, there is suggested a structure made such that the outer race of the bearing and the synthetic resin tire are integrally bridge-welded by cooling and hardening the synthetic resin temporarily thermally dissolved on an outer peripheral surface of the outer race, in place of simply bonding them by applying an adhesive material.
Further, in order to ensure that the tire adhered to the outer peripheral surface of the outer race in the bearing is integrally adhered to the outer race of the bearing in a stronger manner, there is suggested a roller structured such that the tire is constituted by two layers comprising a soft synthetic resin and a hard synthetic resin, an inner tire made of the hard synthetic resin, which is directly adhered to the outer peripheral surface of the outer race in the bearing so as to obtain a stronger adhesion force, and an outer tire made of the soft synthetic resin, which is adhered in such a manner as to overlap with the hard synthetic resin inner tire, whereby the tire having two layers is adhered to the outer peripheral surface of the outer race of the bearing in a stronger manner.
Further, in the roller to which this kind of synthetic resin tire is mounted, in order to integrally adhere the synthetic resin tire having the two, hard and soft layers to the outer race of the bearing, the tire has been produced by a method of integrally providing the soft resin tire outer peripheral portion on the outer peripheral surface of the hard synthetic resin tire base portion in a surrounding manner after adhering the hard synthetic resin tire base portion to the outer race of the bearing.
Further, in a method of producing a synthetic resin wheel, there is suggested a producing method comprising steps of forming a tire portion with a soft synthetic resin having a forming temperature lower than that of a wheel portion, and forming the wheel portion along an inner side of the tire portion with a hard synthetic resin having a forming temperature higher than that of the tire portion.
In this kind of conventional roller, the synthetic resin tire is integrally adhered to the outer peripheral surface of the outer race in the bearing. Further, since the outer peripheral surface of the outer race in this kind of bearing is formed into a smooth surface, a strong adhesion force above a certain level cannot be expected from the adhesive material between the synthetic resin tire adhered by the adhesive material or the like and the outer peripheral surface of the outer race. Accordingly, the synthetic resin tire integrally adhered to the outer race cannot stand against the heavy load and the high speed rotation over a certain level when being used in elevators, escalators and the like, so that the adhesion between the outer race and the tire is separated and the tire slips on the outer race of the bearing. In the worst case, there is a problem in that the tire is taken out from the outer race of the bearing so as to slip off.
Further, in order that the outer race of the bearing and the synthetic resin tire are more firmly adhered to each other, the structure is made so as to firmly adhere the synthetic resin tire on the outer peripheral surface of the outer race by cooling and hardening the temporarily dissolved synthetic resin on the outer race of the bearing, in place of simply applying the adhesive material. In this structure, in comparison with the structure simply bonded by an application of the adhesive material, a strong adhesion force can be obtained. However, in this kind of roller used in elevators, escalators, transfer rollers and the like, there is a possibility that a significantly heavy load is applied at a starting time or at a time of a sudden stop, and in severe using conditions, it is necessary to rapidly stop the high speed rotating roller at a time of high speed rotation, or a sudden stop is required. As a result, there is a problem in that the adhesion between the tire and the outer race of the bearing is damaged and peeled off during the use, so that the tire slips on the outer race and falls off from the outer race.
Further, in order that the tire adhered to the outer peripheral surface of the outer race in the bearing is integrally adhered to the outer race of the bearing in a stronger manner, the structure is made so that the tire is constituted by two layers comprising a soft synthetic resin and a hard synthetic resin, an inner tire made of the hard synthetic resin being directly adhered to the outer peripheral surface of the outer race in the bearing so as to obtain a stronger adhesion force, and an outer tire made of the soft synthetic resin being adhered in such a manner as to overlap with the hard synthetic resin inner tire, whereby the tire having two layers is adhered to the outer peripheral surface of the outer race of the bearing in a stronger manner. In this roller, in comparison with the structure made so as to integrally adhere the tire to the outer race by bonding the synthetic resin tire by an application of adhesive material or cooling and hardening the thermally dissolved synthetic resin on the outer race, a more firm adhesion force can be obtained. However, a load of some hundreds of kilograms per sq. cm. be applied, and a high speed rotation of some thousands per minute may be used. In such case, the adhesion between the tire and the outer race of the bearing is damaged, and the tire peels off during the use, so that there is a problem in that the tire races on the outer race and falls off from the outer race.
Further, in a conventional method of integrally providing the soft resin tire outer peripheral portion on the outer peripheral surface of the hard synthetic resin tire base portion in a surrounding manner after adhering the hard synthetic resin tire base portion to the outer race of the bearing, when the soft synthetic resin tire outer peripheral portion is adhered onto the outer peripheral surface of the tire base portion in a surrounding manner, since a sealing performance of the tire outer peripheral portion with respect to the tire base portion is deteriorated, it is necessary to firmly bond the tire outer peripheral portion to the tire base portion by the adhesive material. Accordingly, a step of uniformly applying the adhesive material to all the surface of the outer peripheral surface with respect to the tire base portion is required, and a problem is caused in that the roller itself is broken due to peeling off from the bonding portion when rotating at a high speed and under a heavy load in the case of bonding by the adhesive material. Further, there is problem in that a high level of skills required for uniformly applying the adhesive material on all the surface of the outer peripheral surface with respect to the tire base portion, so that a producing step is complex and a producing cost is increased.
Further, in the roller which is exposed to the heavy load and stopped for a sufficiently long time, such as in an escalator and the like, when using this kind of conventional roller to which the conventional soft synthetic resin tire is mounted, the synthetic resin tire cannot stand against the heavy load while the rotating operation of the roller is stopped, so that there is a problem in that the portion to which the load is applied is pressed, deformed and recessed (thus reaching a so-called abraded state) and an expansion is formed on the tire in front of and at the back of a rotating direction of the roller, thereby disturbing the rotation of the roller at the starting time.
Further, in the method of producing the synthetic resin wheel disclosed in Japanese Patent Laid-Open No. 297606/1994, which comprises the steps of forming a tire portion by a soft synthetic resin having a forming temperature lower than that of the wheel portion, and forming a wheel portion along the inner side of the tire portion by a hard synthetic resin having a forming temperature higher than that of the tire portion, since the tire portion is formed by the soft synthetic resin having the forming temperature lower than that of the wheel portion and the wheel portion is formed along the inner side of the tire portion by the hard synthetic resin having a forming temperature higher than that of the tire portion, it is excellent that the soft synthetic resin tire portion and the hard synthetic resin wheel portion are integrally welded without using the adhesive material. However, it is necessary to mount the metal bearing by bonding to the inner side of the wheel portion of the integrally welded tire portion and wheel portion. Accordingly, in this roller for an escalator and the like, which is mounted to a heavy load and high speed rotation, and in which the abrasion resistance and a certain elastic force are required, there is a problem in that the adhesion between the bearing and the wheel portion by the adhesive material is peeled off.
Further, in the method of producing the synthetic resin wheel disclosed in Japanese Patent Laid-Open No. 297606/1994, comprising the steps of forming a tire portion by a soft synthetic resin having a forming temperature lower than that of the wheel portion, and forming a wheel portion along the inner side of the tire portion by a hard synthetic resin having a forming temperature higher than that of the tire portion, since the wheel portion is integrally formed along the inner side of the tire portion and the bearing is later inserted and mounted to the wheel portion, the wheel portion cannot be integrally welded to the tire portion and the bearing at the same time, so that there is a problem in that a step for mounting and fixing the bearing to the wheel portion is required. Further, when it is intended to pour the hard synthetic resin having a forming temperature higher than that of the soft synthetic resin in the tire portion, so as to charge and integrally weld the bearing with the wheel portion at the same time as providing the wheel portion in the inner side of the tire portion, that is, for forming the wheel portion between the tire portion and the bearing by the method of producing the synthetic resin wheel disclosed in Japanese Patent Laid-Open No. 297606/1994, comprising the steps of forming a tire portion by a soft synthetic resin having a forming temperature lower than that of the wheel portion and forming a wheel portion along the inner side of the tire portion by a hard synthetic resin having a forming temperature higher than that of the tire portion, a gas is generated on a contact surface between the poured hard synthetic resin and the soft synthetic resin in the tire portion, and the tire portion and the wheel portion cannot be completely welded all over the surface due to the generated gas, that is only a part which is not influenced by the gas is welded, so that there is a problem in that the tire portion and the wheel portion are peeled off when used for escalator roller and the like, which rotates at a high speed and is exposed to a heavy load.
Further, in Japanese Patent Laid-Open No. 279244/1998, a roller is disclosed which comprises a bearing and a tire mounted on the roller and comprised of an inner portion and an outer portion. However, in this roller, the inner portion of the tire covers the outer peripheral surface of the bearing as well as partially the lateral sides adjacent to the outer peripheral surface. The outer portion of the tire covers the outer peripheral surface of the inner portion as well as completely the lateral sides of the inner portion. Thus, the inner portion is not exposed laterally, but is covered by the outer portion. In a method of producing this roller, the inner portion must be provided first, and then the outer portion is provided on the inner portion.
An object of the present invention is to solve the technical problem of this kind of conventional roller structured so as to integrally adhere the synthetic resin tire to the outer race of the bearing.
According to a first aspect of the present invention, a roller includes a bearing having an inner race and an outer race, a tire mounted on the outer race, and means for engaging the tire with the outer race, wherein the tire is integrally welded to an outer peripheral surface of the outer race, whereby the tire is immovably fixed to the bearing.
According to a second aspect of the present invention, a roller includes a bearing having an inner race and an outer race, and a tire mounted on the outer race, wherein the outer race of the bearing is formed to have an uneven outer peripheral surface, and wherein the tire is integrally welded to the uneven outer peripheral surface of the outer race, whereby the tire is immovably fixed to the bearing.
It is preferable that the tire includes a tire base or inner portion made of a hard synthetic resin and a tire outer peripheral portion made of a soft synthetic resin, wherein an outer peripheral surface of the tire base portion is formed to have a concave cross-sectional shape, and wherein the outer peripheral portion of the tire base portion is welded to an inner peripheral surface of the tire outer peripheral portion.
The uneven outer peripheral surface of the outer race may include a flat outer peripheral surface and one or a plurality of grooves formed thereon.
The uneven outer peripheral surface of the outer race may include a flat outer peripheral surface and one or a plurality of protrusions formed thereon.
The uneven outer peripheral surface of the outer race may include a flat outer peripheral surface and a plurality of grooves formed thereon, and the plurality of grooves may be spaced in parallel to each other and extend in an axial direction of the bearing.
In the alternative, the plurality of grooves may be spaced in parallel to each other and extend in a spiral manner in an axial direction of the bearing; or the plurality of grooves may extend in a spiral manner in an axial direction of the bearing so that the grooves cross each other on the outer peripheral surface of the outer race.
It is preferable that a thickness of the outer race is set to have a thickness obtained by adding a depth of the groove to a thickness of an outer race of a standard bearing in accordance with an international standard.
It is preferable that the inner race of the bearing has an end which protrudes from a side surface of the tire, or the inner race of the bearing has both ends which protrude from the respective side surfaces of the tire.
According to a third aspect of the present invention, a method of producing a roller comprising a bearing and a tire mounted on the bearing includes the steps of arranging the bearing concentrically in an inner space of a tire outer peripheral portion of a tire so as to form a gap therebetween, the tire outer peripheral portion being made of soft synthetic resin, and pouring a hard synthetic resin having a melting point higher than that of the soft synthetic resin into the gap to form the tire base portion, whereby said tire base portion is integrally welded to the bearing and the tire outer peripheral portion.
According to a forth aspect of the present invention, a method of producing a roller comprising a bearing and a tire mounted on the bearing includes the steps of arranging the bearing concentrically in an inner space of a tire outer peripheral portion of a tire so as to form a gap therebetween, the bearing including an outer race having an uneven outer peripheral surface, the tire outer peripheral portion being made of soft synthetic resin, and pouring a hard synthetic resin having a melting point higher than that of the soft synthetic resin into the gap to form the tire base portion, whereby said tire base portion is integrally welded to the bearing and the tire outer peripheral portion.
According to a fifth aspect of the present invention, a method of producing a roller comprising a bearing and a tire mounted on the bearing includes the steps of arranging the bearing concentrically in an inner space of a tire outer peripheral portion of a tire so as to form a gap therebetween, the bearing including an outer race having an uneven outer peripheral surface, the tire outer peripheral portion being made of soft synthetic resin having a melting point of 190xc2x0 C., and pouring a hard synthetic resin having a melting point of 210xc2x0 C. into the gap to form the tire base portion, whereby said tire base portion is integrally welded to the bearing and the tire outer peripheral portion.
According to a sixth aspect of the present invention, a method of producing a roller comprising a bearing and a tire mounted on the bearing includes the steps of arranging the bearing concentrically in an inner space of a tire outer peripheral portion of a tire so as to form a gap therebetween, the bearing including an outer race having an uneven outer peripheral surface, the tire outer peripheral portion being made of soft polyurethane rubber having a melting point of 190xc2x0 C., and pouring a heated and melt thermoplastic hard urethane rubber having a melting point of 210xc2x0 C. into the gap to form the tire base portion, so that a part of the soft polyurethane rubber on the surface of the tire outer peripheral portion is dissolved and mixed to the thermoplastic hard urethane rubber, whereby said tire base portion is integrally welded to the bearing and the tire outer peripheral portion.
The roller according to the present invention advantageously has an inner portion of the tire which is at least partially exposed on a side surface of the tire. For example, the outer portion of the tire is only welded to the outer peripheral surface of the inner portion.
In the roller according to the present invention, advantageously, the inner portion of the tire has an uneven outer peripheral surface, and/or the outer portion of the tire has an uneven inner peripheral surface, so that the inner portion and the outer portion of the tire are strongly welded to each other.
Other objects and advantages of the present invention will become apparent from the description of the preferred embodiments, which may be modified in any manner without departing from the scope and spirit of the present invention.